Thickness errors elimination in wound plastics foil

摘要

Prodn. of thermoplastic foil (1) and winding it into a coil (2) whilst keeping the coil free from thickness errors induced by the extrusion and winding process comprises: monitoring the coil thickness and contour by a monitoring system (8) which produces signals to a computor (12) which compares these signals with pref. valves and produces feedback control to the foil thickness adjuster (5) at the extrusion die and blowing head (3,4). The measured thickness and contour errors may be above or below pref. valves and are measured over wound coil layers. This provides an inverse error signal via the computer to the die, etc.